1. Field of the Invention
The present invention relates to an apparatus for manufacturing a roof lining for automobiles and more particularly to an apparatus for manufacturing a roof lining made of thermoplastic material.
2. Prior Art
The inside of a roof of an automobile is usually lined with a roof lining made of cloth, polyvinylchloride sheet or the like material with an insulator interposed therebetween. There are two types of roof linings. One is formed such that sagging of the roof lining is prevented by means of a plurality of resting wires extending in the transverse direction. The other type of lining is formed in a composite structure consisting of a matrix of cardboard, felt-like material with plastic material impregnated therein or the like, and a lining layer of cloth or the like material both are thermally adhered to one another with an adhesive interposed therebetween with the aid of a hot press.
The present invention is of the first type roof lining which is constructed by a sheet made of thermoplastic material with a plurality of elongated wire pockets integrally formed on the sheet through which a resting wire is inserted.
The conventional roof lining is typically illustrated in FIGS. 9 and 10. As is apparent from the drawings, the wire pockets are formed with several different materials on the roof lining. The wire pockets are welded to the lining with thermal energy generated by high frequency current.
Normally, the welding with high frequency current is manually carried out for each of the welding spots on the wire pockets. An improved apparatus, semi-automatic welding apparatus, can be employed too. The apparatus works such that when a sheet material is placed around the periphery of a drum, the drum rotates at a certain angle. When the drum stops, another sheet material is manually placed thereon. Welding is then carried out for thermally adhering the sheet materials to one another with high frequency current. Such steps are repeated for several times to form the wire pockets.
However, it is found that the manual or semi-automatic type of apparatus for manufacturing a roof lining as described above has low productivity, fluctuation in quality, high rate of material consumption with high manufacturing cost. As a result, it fails to meet the needs of manufacturers whose business activities cannot last any longer unless high productivity improved quality and reduced manufacturing costs are assured.